The invention is directed towards batteries, in particular, batteries used in battery operated devices. The invention relates to battery arrangements that result in safe and reliable operation of battery powered devices. This invention may be used with external defibrillators, including automatic or semi-automatic external defibrillators (xe2x80x9cAEDsxe2x80x9d), manual defibrillators and defibrillator trainers.
Battery operated devices find diverse applications ranging from small and simple children""s toys to sophisticated laptop computers and large electric powered vehicles. When batteries are used in medical devices, such as automatic or semiautomatic external defibrillators (AEDs), manual defibrillators, the performance of the batteries may determine whether a patient lives or dies. An example of an AED that uses batteries is described in Cameron et al., U.S. Pat. No. 5,803,927 entitled xe2x80x9cElectrotherapy Method and Apparatus for External Defibrillation,xe2x80x9d the specification of which is incorporated herein.
A typical battery cell includes an anode, a cathode, an electrolyte and a housing. A chemical reaction takes place between the anode and cathode. The anode and the cathode have different tendencies to gain or lose electrons. This difference in electron affinity in harnessed in a chemical reaction to accomplish useful work. The amount of work or energy available depends on the magnitude of the electron affinity difference and quantity of the anode and cathode materials available for the chemical reaction. The difference in affinity is a function of the battery chemistry of the battery cell.
There are many factors to consider when choosing battery chemistry, the type of active materials used for the anode and cathode as well as the electrolyte composition, for a particular application. These include voltage, current, and capacity requirements of the battery operated device, in addition to weight, cost, shelf life, toxicity, recyclability, and operating temperature range. A non-rechargeable battery, also referred to as a primary battery, is discarded at the end of its operational life. A rechargeable battery, also referred to as a secondary battery, is recharged after discharge throughout its operational use. Once a battery chemistry is chosen, a number of individual cells having the same voltage and capacity may be connected in series, parallel, or series and parallel to form a battery module. In designing a battery module to obtain the required capacity, it is common practice to use fewer cells of larger capacity, that is cells with larger quantities of active materials to reduce the total weight and cost of the battery module.
Cameron et al. discusses battery reliability in U.S. Pat. No. 5,483,165 entitled xe2x80x9cBattery System and Method for Determining a Battery Condition,xe2x80x9d the specification of which is incorporated herein. Cameron discloses a battery monitor and capacity indicator that uses a sense cell to determine the remaining capacity and depletion condition of the main battery.
Reference should be made to the detailed description of the preferred embodiments.
Operator safety and power source reliability is of critical importance for any battery module, but even more so if it powers a medical device. When a battery module is assembled it is common practice that external safety devices, such as electrical fuses and thermal switches, are incorporated. These safety devices limit the current and temperature of the battery cells, but do not necessarily protect against an internal short circuit, a rapid change in the chemical reaction, or severe mechanical stress. A safety vent internal to the battery cell serves to protect against these faults by venting its contents to shut down the chemical reaction and relieve internal pressure and temperature build-up. However, in some instances and under some conditions, the cell can not vent quickly enough to prevent the cell from exploding or rupturing. In addition, some battery chemistries vent hazardous products, which may be any combination of reactive, corrosive, toxic, and flammable. The battery module output can deteriorate and there is a danger of explosion and fire due to heat generation or ignition. This can result in an unsafe situation for the operator and others in the vicinity of the device, particularly when used in a confined space, such as in an airplane. This can also result in the failure of the device, which in the case of a medical device may result in patient death. There have been instances of battery modules rupturing in medical devices which resulted in physical injury. Therefore, what is needed is a reliable battery module that maximizes safety for medical emergency use.
This invention is directed to a battery module capable of delivering greater than 1 KiloJoule (KJ), comprising more than 6 lithium cells, each lithium cell containing either less than 2.0 grams of lithium or less than 10.0 grams of manganese dioxide, electrically connected in series, parallel, or both series and parallel. The battery module may be either primary or secondary. In another embodiment, the battery module is capable of delivering greater than 85 KJ, comprising a plurality of lithium cells, each lithium cell containing either less than 2.0 grams of lithium or less than 10.0 grams of manganese dioxide, electrically connected in series, parallel, or both series and parallel. The battery module may be either primary or secondary. In yet another embodiment, the battery module is capable of delivering less than 84 KJ, comprising a plurality of lithium cells, each lithium cell containing either less than 2.0 grams of lithium or less than 10.0 grams of manganese dioxide, electrically connected in series, parallel, or both series and parallel. The battery module may be either primary or secondary.
In another embodiment, an external defibrillator, comprising a battery module capable of delivering greater than 1 KJ throughout its operational life, including, more than 6 lithium cells, each lithium cell containing either less than 2.0 grams of lithium or less than 10.0 grams of manganese dioxide, electrically connected in series, parallel, or both series and parallel. The battery module provides power to the external defibrillator. In a preferred embodiment, the external defibrillator delivers a biphasic waveform to a patient. The battery module may be either primary or secondary. In another embodiment, an external defibrillator comprising a battery module capable of delivering greater than 85 KJ throughout its operational life, including, a plurality of lithium cells, each lithium cell containing either less than 2.0 grams of lithium or less than 10.0 grams of manganese dioxide, electrically connected in series, parallel, or both series and parallel. The battery module provides power to the external defibrillator. In a preferred embodiment, the external defibrillator delivers a biphasic waveform to a patient. The battery module can be either primary or secondary. In yet another embodiment, an external defibrillator, comprising a battery module capable of delivering less than 84 KJ, including, a plurality of lithium cells, each lithium cell containing either less than 2.0 grams of lithium or less than 10.0 grams of manganese dioxide, electrically connected in series, parallel, or both series and parallel. The battery module provides power to the external defibrillator. In a preferred embodiment, the external defibrillator delivers a biphasic waveform to a patient. The battery module can be either primary or secondary.
Another embodiment of this invention is a battery module capable of delivering greater than 1 KJ throughout its operational life, comprising a plurality of lithium cells, each lithium cell containing either less than 21 grams of sulfur dioxide or less than 15 grams of thionyl chloride, electrically connected in series, parallel, or both series and parallel. In yet another embodiment, an external defibrillator, comprising a battery module capable of delivering greater than 1 KJ throughout its operational life, including, a plurality of lithium cells, each lithium cell containing either less than 21 grams of sulfur dioxide or less than 15 grams of thionyl chloride, electrically connected in series, parallel, or both series and parallel. The battery module provides power to the external defibrillator. Preferrably, the external defibrillator delivers a biphasic waveform to a patient.
An embodiment of this invention is a method of optimizing a battery module, including a plurality of cells, for safe operation, comprising the steps of: determining voltage and capacity requirements; determining if primary or secondary battery cells should be used; determining a battery chemistry for the battery cells; determining the quantity of active material in the battery cell; and determining the number of cells to be electrically connected in series, parallel, or both series and parallel.
For a full understanding of the present invention, reference should be made to the detailed description of the preferred embodiments and to the accompanying drawings. However, other features and advantages of the present invention will be apparent to persons of skill in the art from the following description of the preferred embodiments, and from the claims.